CASR and neonatal severe primary hyperparathyroidism: Activing mutations of CaSR lead to autosomal dominant hypocalemia (ADH), while heterozygous or homozygous inactivating mutations of CaSR lead to different extents of hypercalcemia accompanied by hypocalciuria, such as familial hypocalciuric hypercalcemia1 (FHH1) and neonatal severe hyperparathyroidism (NSHPT).